Can anyone spot what it is I am doing wrong? It's starting to feel like a flashback of school, where the teacher comes up behind you and points out the missing period or semicolon in one line of code that you have been trying to debug for three hours.

ok, I don't quite grok the format of the .vn file, I just copied what was in the article about Split DNS for Zimbra. All my previous experience with DNS has been using the web interface at domainpeople.com.

You are not providing the complete picture for your Internal network. Don't you have an Internal DNS already? Is Zimbra the only server in your environment?

If you are try to bring up the Internal DNS on Zimbra. most of these changes looks okay except you need to move the MX line above mail. The MX is for the domain and not the mail server. Then you just need to start the named service.